Phase shifted surface emitting DFB laser structures with gain or absorptive gratings

A surface emitting semiconductor laser comprising:

• a semiconductor lasing structure having an active layer, opposed cladding layers contiguous to said active layer, a substrate, and electrodes by which current can be injected into said semiconductor lasing structure, and
• a distributed diffraction grating associated with an active layer of said lasing structure, said distributed diffraction grating having periodically alternating grating elements, each of said grating elements having a gain effect wherein any adjacent pair of grating elements includes one element having a relatively high gain effect and one having a relatively low gain effect wherein, a difference in such gain effects causes an output signal in the range of 910 nm to 990 nm, or 1200 nm to 1700 nm and wherein said grating includes a phase shifter to alter an output mode profile to facilitate coupling said output to a fibre, and a means to ameliorate longitudinal spatial hole burning.

A surface emitting semiconductor laser for producing output signals of defined spatial characteristics said laser comprising;

• a semiconductor lasing structure having an active layer, opposed cladding layers contiguous to said active layer, a substrate and electrodes by which current can be injected into said semiconductor lasing structure to produce an output signal in a telecommunications band and a distributed diffraction grating having a phase shifter sized and shaped to provide, upon the injection of current into the lasing structure, mode profile to facilitate coupling said output signal to an optical fibre.